CVE-2026-39407

ADVISORY - github

Summary

Summary

A path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path.

When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass.

Details

The routing layer and serveStatic handle repeated slashes differently.

For example:

/admin/secret.txt => matches /admin/*
/admin//secret.txt => may not match /admin/*

However, serveStatic may interpret both paths as the same file location (e.g., admin/secret.txt) and return the file.

This inconsistency allows a request such as:

GET //admin/secret.txt

to bypass middleware registered on /admin/* and access protected files.

The issue has been fixed by rejecting paths that contain repeated slashes, ensuring consistent behavior between route matching and static file resolution.

Impact

An attacker can access static files that are intended to be protected by route-based middleware by using repeated slashes in the request path.

This can lead to unauthorized access to sensitive files under the static root.

This issue affects applications that rely on serveStatic together with route-based middleware for access control.

Common Weakness Enumeration (CWE)

ADVISORY - nist

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

ADVISORY - github

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')


GitHub

CREATED

UPDATED

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.3medium
PackageTypeOS NameOS VersionAffected RangesFix Versions
hononpm--<4.12.124.12.12

CVSS:3 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.

The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone). One example of an Adjacent attack would be an ARP (IPv4) or neighbor discovery (IPv6) flood leading to a denial of service on the local LAN segment (e.g., CVE-2013-6014).

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

The vulnerable system can be exploited without interaction from any user.

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.

There is no loss of trust or accuracy within the impacted component.

There is no impact to availability within the impacted component.

NIST

CREATED

UPDATED

EXPLOITABILITY SCORE

3.9

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

5.3medium

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-f5qq-7g8r-h66w

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-j2gg-532p-r6g8

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY